Why Pseudo 3d?
Now that every system can produce graphics consisting of a zillion polygons on the fly, why would you want to do a road the old way? Aren’t polygons the exact same thing, only better? Well, no. It’s true that polygons lead to less distortion, but it is the warping in these old engines that give the surreal, exhillerating sense of speed found in many pre-polygon games. Think of the view as being controlled by a camera. As you take a curve in a game which uses one of these engines, it seems to look around the curve. Then, as the road straightens, the view straightens. As you go over a blind curve, the camera would seem to peer down over the ridge. And, since these games do not use a traditional track format with perfect spatial relationships, it is possible to effortlessly create tracks large enough that the player can go at ridiculous speeds– without worrying about an object appearing on the track faster than the player can possibly react since the physical reality of the game can easily be tailored to the gameplay style.
But they have plenty of drawbacks as well. The depth of physics found in more simulation-like games tends to be lost, and so these engines aren’t suited to every purpose. They are, however, easy to implement, run quickly, and are generally a lot of fun to play with!
It is worth noting that not every older racing game used these techniques. In fact, the method outlined here is only one possible way to do a pseudo 3d road. Some used projected and scaled sprites, others seem to involve varying degrees of real projection for the road. How you blend real mathematics with trickery is up to you. I hope you have as much fun exploring this special effect as I did.